package network;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;

import static java.lang.System.out;

/**
 * Created with IntelliJ IDEA.
 * Description:TCP Socket 实现的回显服务器
 * User: 邓大帅
 * Date: 2024-01-27
 * Time: 19:52
 */
public class TcpEchoServer {
    private ServerSocket serverSocket = null;
    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }
    public void start() throws IOException {
        System.out.println("服务器启动!");
        ExecutorService executorService = Executors.newCachedThreadPool();
        while (true) {
            Socket clientSocket = serverSocket.accept();
//            这里要创建线程来调用processConnection，不然只能处理一个客户端
//            创建线程后，主线程继续在当前循环跑，创建的一个线程去执行processConnection服务一个客户端
//            Thread thread = new Thread(() -> {
//                try {
//                    processConnection(clientSocket);
//                } catch (IOException e) {
//                    e.printStackTrace();
//                }
//            });
//            thread.start();
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    try {
                        processConnection(clientSocket);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            });
        }

    }

    private void processConnection(Socket clientSocket) throws IOException {
        System.out.printf("[%s:%d] 客户端上线\n",clientSocket.getInetAddress().toString(),clientSocket.getPort());
        try (InputStream inputStream = clientSocket.getInputStream();
             OutputStream outputStream = clientSocket.getOutputStream()) {
            Scanner scanner = new Scanner(inputStream);
            PrintWriter writer = new PrintWriter(outputStream);
            while (true) {
//                这里第二次运行到hasNext会阻塞等待，当输入源未关闭时
                if (!scanner.hasNext()) {
                    System.out.printf("[%s:%d] 客户端下线!\n",clientSocket.getInetAddress().toString(),clientSocket.getPort());
                    break;
                }
                String request = scanner.next();
                String response = process(request);
                writer.println(response);
                writer.flush();
                System.out.printf("[%s:%d] req: %s res: %s\n",clientSocket.getInetAddress().toString(),clientSocket.getPort(),
                        request,response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            clientSocket.close();
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer tcpEchoServer = new TcpEchoServer(9090);
        tcpEchoServer.start();
    }
}
